I have a leak on the diff of my 73 torino. I want to up grade to a limited slip locker. Don't have the cash for the locker but I have to open up everything to put in new seals. I am considering just keeping the fluid full and waiting to fix the leak and upgrade at the same time. Is this a good plan?Mark

Really depends on the location of the leak and/or the process that will take to correctly fix said leak. That said if it were me I would fix the leak no matter what(absolutely hate leaks), but If not too bad, keep an eye on the fluid level and fix everything at one time.

I replaced everything in mine and it still leaks a little. Nothing crazy but always leaves a small oil spot on the floor of the garage. Wait until you're ready for an overhaul then try your luck at replacing seals and stuff. Keep the fluid level up in the meantime and you should be fine.

Thanks guys, common sense prevails. It looks to be leaking from where the shaft mounts to the spindle and also from the area where the 10 bolt gasket goes. I have all of the seals, I just don't want to pull apart that heavy diff twice. Rebuilt a Dana 44 front end on a 95 Bronco and that was heavy. This looks bigger. I will attach some photos here as well if I can.

When you get to removing it, make sure you place a mark(use ring and pinion pattern grease) where the pinion gear meshes with the ring gear teeth to keep them "timed" before you remove the pinion support from the center section housing(not sure if your R-n-P set is a hunting or non-hunting gearset-better to be safe and mark 'em than be sorry you didn't). Once you remove the pinion support have a close look at each of the blind bolt cavities in the center section that holds the pinion support bolts, make sure they are all sealed, I had a leak and couldn't figure it out till I removed the pinion support. I found a pin-hole in one of the blind cavities which allowed gear oil to migrate past one of the bolts and leave spots on my floor . When you go to replace the pinion seal be wary of the crush sleeve, it is supposed to be a one time use only part. Now you could order this or one set like it, makes life MUCH easier:

and use the crush sleeve for measurement reference and install the solid spacer and necessary shims to match the crush sleeve. Using this solid spacer/shim method will allow future seal replacements or any other work without changing pre-load on the pinion bearings. A new pinion nut is advisable, a bit of Lok-tite on threads will keep gear oil from migrating past the pinion shaft threads even if you re-use the old pinion nut. Also make sure you have a new pinion support O-ring, they are usually square cut. Hope this helps.

There are some gear sets that have certain teeth that exactly mesh every 2-5 revolutions, these are timed gear sets(non-hunting), if you do not put them back together like set at factory you could get a vibration and/or have a noisy differential. This explanation taken from here:

Gear sets are hunting, non-hunting and partial non-hunting depending on the ratio. Of these I understand two briefly as:

Hunting. A set of hypoid gears whose ratio is not evenly divisible. Example: 3.55 As the ring gear rotates, the pinion passes every tooth on the ring gear resulting in an even wear pattern around the entire ring.

Non-hunting. A set of hypoid gears whose ration is evenly divisible. Example: 3.25 As the ring gear rotates, the pinion teeth only contact a fraction of the ring gear teeth as the ring rotates. This happens because the teeth match up for each rotation and hence produce several wear patterns on the ring. These have to be indexed before disassembly since elsewise the lack of pattern match causes excess wear and tear when set is reassembled. Note well the initial pattern on the pinion/ring no longer matches the pattern on the pinion/ring when not indexed; hence a new wear pattern must evolve and this causes whining, noise and early failure of the set.

Here is a link explaining the same with a chart on hunting and non-hunting gear ratios

Short answer is yes, there are "timed" gear sets. I had my 9 3/8" 3.25 center section rebuilt with new Trac-Lok clutches, bearings and seals. Once installed I found it had a rolling type of roaring noise, sounded/felt like a bearing was bad. I removed the center section and found that it still had the factory paint that marked where the ring should mesh with the pinion, this mesh point was off a few teeth no matter how many times I revolved the ring and pinion. I removed the pinion support and matched the factory assembled mesh and no more noise/vibration.

if the tooth count numbers line up for a constant pattern, there'll be a repeating wear pattern on the ring gear that matches a specific tooth on the pinion. if the tooth count makes a 'prime number' then it's possible the teeth will never see each other again ... at least not often or exclusively

Thanks for the great knowledge. The leak appears to be right where the drive shaft connects to the u joint. I think that is the spindle. Anyway the rest looks good. I am definately going to wait until I.am read to buy the parts to up grade to the limited slip rearend. The ball joints were a bear to get out, the upper ones..lower ones were easy. Have a great week

nearest gear oil to the flange can be oil coming through the threads between the flange nut and the pinion gear. the nut has a sealer applied on the back side to seal the threads, it's a one time use nut as far as the sealer goes. popular procedure is to use extra sealer on the threads especially if a pinion seal is getting changed or for any reason the nut gets loosened or removed, even if a new nut gets installed, the applied sealer isn't very reliable

next leak point back is the pinion seal itself, pretty self-explanatory

so let me get this right... they aren't timed initially or just need to go back in the same timed mesh if they are reused???

even if there's a timing mark, there's no wear pattern set in from new. if you're dis-assembling it and you find timing marks are not lined up like they were ignored during original assembly, make & use your own marks to get the gears back the way they were found

if the ring gear tooth count is divisible by the pinion gear tooth count, it's a timed set

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